Quantum-chemical studies of amide–iminol tautomerism for inhibitor of lactate dehydrogenase: Oxamic acid

Raczyńska, Ewa D.; Hallmann, M.; Duczmal, Kinga

doi:10.1016/j.comptc.2011.01.017

Cited by 12 publications

(21 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These variations influence π-electron delocalization in the ring (six atoms) and also in the whole tautomeric system (seven atoms including the exo N atom). In this paper, we quantitatively measured the changes of π-electron delocalization by means of the geometry based harmonic oscillator model of electron delocalization (HOMED) index [6, 7, 35, 45–48] which describes well any type of conjugation (π-π, n-π, and σ-π) possible in heteroatomic systems. This index was applied here to the DFT-calculated bond lengths.…”

Section: Resultsmentioning

confidence: 99%

“…The HOMED procedure has been described in detail in ref [46] and applied to various cyclic and acyclic π-electron systems containing heteroatoms [6, 7, 35, 45–48]. The HOMED index is based on the original harmonic oscillator model of aromaticity (HOMA) index [49, 50].…”

Section: Homed Indicesmentioning

confidence: 99%

“…The HOMA index reformulated in 1993 [51] seems to be inappropriate for π-electron delocalized systems containing heteroatoms. The main reason is a use of different measures of π-electron delocalization for the reference CC and CX bonds [6, 7, 35, 45–48]. The reformulated HOMA index can be solely applied for homoaromatics.…”

Section: Homed Indicesmentioning

confidence: 99%

See 2 more Smart Citations

DFT studies on one-electron oxidation and one-electron reduction for 2- and 4-aminopyridines

2012

Self Cite

View full text Add to dashboard Cite

Quantum-chemical calculations {DFT(B3LYP)/6-311+G(d,p)} were performed for all possible tautomers (aromatic and nonaromatic) of neutral 2- and 4-aminopyridines and their oxidized and reduced forms. One-electron oxidation has no important effect on the tautomeric preference for 2-aminopyridine. The amine tautomer is favored. However, oxidation increases the stability of the imine NH tautomer, and its contribution in the tautomeric mixture cannot be neglected. In the case of 4-aminopyridine, one-electron oxidation increases the stability of both the amine and imine NH tautomers. Consequently, they possess very close energies. As major tautomers, they dictate the composition of the tautomeric mixture. The CH tautomers may be considered as very rare forms for both neutral and oxidized aminopyridines. A reverse situation takes place for the reduced forms of aminopyridines. One-electron reduction favors the C3 atom for the labile proton for both aminopyridines. This may partially explain the origin of the CH tautomers for the anionic states of nucleobases containing the exo NH2 group.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Homed Indicesmentioning

confidence: 99%

See 1 more Smart Citation

DFT studies on one-electron oxidation and one-electron reduction for 2- and 4-aminopyridines

2012

Self Cite

View full text Add to dashboard Cite

show abstract

“…The abbreviation HOMED was proposed in 2006 for the modified index [63], but it may also be abbreviated as moHOMA (modified original HOMA) or simply HOMA. The HOMA (harmonic oscillator model of aromaticity) index [65,66], reformulated by Krygowski [67], and the HOMHED (harmonic oscillator model of heterocyclic electron delocalization) index, proposed by Frizzo and Martins in 2012 [68] and based on hypotheses of the HOMED index [64], were not applied here for cytosine.…”

Section: Methodsmentioning

confidence: 99%

“…To properly determine the distribution of p-and nelectrons for all tautomers/rotamers of cytosine and to well describe the variations of electron delocalization, the geometry-based HOMED (harmonic oscillator model of electron delocalization) procedure [63,64] was applied to the geometries optimized at the DFT(B3LYP)/6-311?G(d,p) level. The abbreviation HOMED was proposed in 2006 for the modified index [63], but it may also be abbreviated as moHOMA (modified original HOMA) or simply HOMA.…”

Section: Methodsmentioning

confidence: 99%

DFT studies on the favored and rare tautomers of neutral and redox cytosine

Raczyńska

Sapuła²,

Zientara‐Rytter³

et al. 2015

Struct Chem

Self Cite

View full text Add to dashboard Cite

The complete tautomeric mixture consisting of nine prototropic tautomers has been studied in the gas phase at the DFT(B3LYP)/6-311?G(d,p) level for neutral, oxidized, and reduced cytosine. Rotational isomerism of the exo -OH group and geometrical isomerism of the exo =NH group have also been considered. Tautomeric conversions possible for cytosine have been compared with those for its structural models, 4-amino-and 2-hydroxypyrimidine. Effects of intramolecular interactions between neighboring groups for cytosine are analogous to those observed for model compounds. Although they are not very strong, they are sufficient to influence tautomeric equilibria and relative stabilities of individual tautomers. One-electron oxidation and one-electron reduction change tautomeric preferences. Tautomers that are rare forms for neutral cytosine become favored ones for oxidized and reduced cytosine. Aromaticity is not the main factor that dictates the tautomeric preferences. Stability of functional groups seems to be more important than full electron delocalization.

show abstract

The σ+π dual aromaticity of typical bi‐tetrazole ring molecule TKX‐50

Yang,

Dong,

et al. 2024

ChemPhysChem

View full text Add to dashboard Cite

Two complexes of dihydroxylammonium 5,5´‐bistetrazole‐1,1´‐diolate (TKX‐50) were employed to evaluate the aromaticity of their tetrazole rings via deep analysis such as the electronic structure, the ZZ component of the natural chemical shielding tensor (NICSZZ) and component orbitals, localized orbital locator purely contributed by σ‐orbitals (LOL‐σ) and localized orbital locator purely contributed by π‐orbitals (LOL‐π), the anisotropy of the induced current density(AICD) and the ZZ component of iso‐chemical shielding surface(ICSSZZ)of these tetrazole rings thereof. The conclusion shows: that all tetrazole rings and bi‐tetrazole rings in complexes have strong σ and a comparable strength π double aromaticity; all these magnetic shields almost symmetrically increase from the central axis to the tetrazole ring atoms; tetrazole rings in complex II show a little stronger dual aromaticity than that in complex I mainly due to the different orientation of the fragment 2 encompassing two hydroxylamine groups resulting in different effects on the contributions of σ orbitals and π orbitals to total aromaticity of tetrazole rings thereof; the difference in aromaticity is fundamentally caused by the atoms O with stronger electron‐withdrawing than atom N in fragment 2 interact with bi‐tetrazole ring through O in complex I but through N in complex II.

show abstract

Quantum-chemical studies of amide–iminol tautomerism for inhibitor of lactate dehydrogenase: Oxamic acid

Cited by 12 publications

References 64 publications

DFT studies on one-electron oxidation and one-electron reduction for 2- and 4-aminopyridines

DFT studies on one-electron oxidation and one-electron reduction for 2- and 4-aminopyridines

DFT studies on the favored and rare tautomers of neutral and redox cytosine

The σ+π dual aromaticity of typical bi‐tetrazole ring molecule TKX‐50

Contact Info

Product

Resources

About